Cooling arrangement for rotary mechanisms



July 3, 1962 w. G. FROEDE ETAL COOLING ARRANGEMENT FOR ROTARY MECHANISMS 5 Sheets-Sheet 1 Filed Oct. 1, 1959 3 an 3 on ERE mm D RD W w A Mm w D my Y N A B H ATTORNEY July 3, 1962 w. G. FROEDE ET AL COOLING ARRANGEMENT FOR ROTARY MECHANISMS 5 Sheets-Sheet 2 Filed Oct. 1, 1.959

INVENTORS WALTER 5.5111250:

ERNET HUPF'NER HAN Nfi'DlETER F'AEEHKE. BY A M ATTDRNEY July 3, 1962 w. G. FROEDE ET AL COOLING ARRANGEMENT FOR ROTARY MECHANISMS 5 Sheets-Sheet 3 Filed Oct. 1, 1959 V we 74 76 I00 H2 no :02 I207 40 1 a Q 3B 20 \Q 42 INVENTORS WALTER agrarian:

ERNEIT HDF'F'NER HANNFI-DIETEP PAEIEHKE ATTORNEY W. G. FROEDE ETAL COOLING ARRANGEMENT FOR ROTARY MECHANISMS July 3, 1962 l 5 Sheets-Sheet 4 Filed Oct. 1, 1959 INVENTOR3 WALT ER El, FFIIJEDE ERNET HE'IFIPNER HANNEI-DIETEH PASEHKE BY A- ATTORNEY July 3, 1962 w. e. FROEDE ETAL 3,

COOLING ARRANGEMENT FOR ROTARY MECHANISMS Filed Oct. 1, 1959 5 Sheets-Sheet 5 178 I52 I84 I80 15s it I86 L- l l I INVENTORS WALTER a. ERDEDE ERNET HI'IIF'PNEFI HANNEr-DIETER PAEICHKE ATT DRNEY Utlit 3,042,009 Patented July 3, 1962 1 3,042,009 COOLING ARRANGEMENT FOR ROTARY MECHANISMS Walter Gray Froede, Neckarsulm, Ernst Hiippner, Furfeld, and Hanns-Dieter Paschke, Neckarsulm, Germany, assignors to NSU Motorenwerke Aktiengesellschaft, Neckarsulm, and Wankel G.m.b.H., Lindau,

Bodensee, Germany Filed Oct. 1, 1959, Ser. No. 843,768 Claims priority, application Germany Oct. 2, 1958 13 Claims. (Cl. 123-8) This invention relates to rotary mechanisms having an outer body with an inner rotor and is particularly directed to means for cooling the inner rotor of such an englue.

The invention is applicable to rotary mechanisms comprising an outer member having an internal cavity with spaced parallel end walls and a multi-lobed peripheral wall and having an inner member or rotor which extends within said cavity, said inner rotor having its end faces fitted between the cavity end walls and having circumferentially-spaced apex portions in engagement with the peripheral wall of said cavity to provide a plurality of working chambers therebetween which vary in volume upon relative rotation of said rotor and outer member. Inasmuch as the outer member has a cavity within which the inner rotor extends, said outer member may be termed a housing for said rotor.

In a known form of this type of engine the outer member or housing is stationary and the inner rotor has a bore therethrough co-axial with the rotor and through which the eccentric portion of a shaft extends for supporting said rotor for rotation about the axis of said eccentric portion so that during engine operation the rotor has a planetary motion within said cavity about the axis of the shaft. In addition the rotor has an internal gear coaxially secured thereto and meshing with a fixed external gear co-axial with said shaft to enforce said planetary motion of the rotor about the shaft axis.

Such rotary mechanisms may be used as fluid motors, fluid pumps and as internal combustion engines. Where the fluid of the mechanism is hot it generally will be neccessary to cool the inner rotor of the mechanism. This is particularly true where the mechanism is used as an internal combustion engine.

It is difficult to circulate a cooling liquid through said inner rotor because of its planetary motion and because the inner rotor does not have a shaft which extends beyond the outer body and through which a cooling liquid could be circulated to and from. the inner rotor.

In another known form of such rotary mechanisms the housing for the rotor instead of being stationary is also a rotor. In this latter form the inner rotor is geared to the outer member or housing and may be journaled on the eccentric portion of a stationary shaft so that, as in the case of a rotary mechanism with a stationary outer body, the inner rotor does not have a shaft which extends beyond the outer rotor through which a cooling liquid can be circulated to and from the inner rotor.

In both of said forms of said rotary mechanisms the fact that the bearing surfaces between the inner rotor and shaft eccentric portion must be lubricated and the fact that the inner rotor and outer member are geared together make it difficult to prevent leakage of the cooling liquid from the inner rotor into the working chambers of the mechanism.

An object of the invention comprises the provision of a novel and effective arrangement for liquid cooling the inner rotor of said rotary mechanisms.

According to the invention the inner rotor of the rotary mechanisms is provided with passages for the flow of a liquid having both cooling and lubricating properties and annular seal means are provided between the end faces of the inner rotor and the adjacent end walls of the outer member to prevent leakage of said liquid into the working chambers of the rotary mechanisms. Said seal means is disposed radially outwardly of the bearing surfaces rotatable supporting the inner rotor on the shaft eccentric portion, radially outwardly of the teeth of the gearing interconnecting the inner rotor and outer member and radially outwardly of the inlet and outlet openings in the inner rotor for the supply and return of the cooling liquid to and from said inner rotor. At least some of the cooling liquid may be used for lubricating the bearings. Also said annular seal means preferably consists of thin-walled rings which are elastically urged into sealing engagement and in which the pressure of the cooling liquid acting on said rings increases the effectiveness of the seal.

Cooling liquid is delivered to and returned from the inner rotor by way of annular chambers which are disposed radially inwardly of said annular seal rings at least at one end face of the inner rotor, and/ or at one end face of the shaft eccentric portion and/or at one end wall of the rotor housing. The cooling liquid can be delivered to such an annular chamber through the adjacent end wall of the rotor housing or through a bearing of the shaft. In the latter arrangement the cooling liquid also serves to lubricate the bearing. Also passages may be provided in the shaft and its essentric portion which terminate at the periphery of said eccentric portion whereby the cooling liquid can be delivered to and returned from the rotor through the bearing between the rotor and the shaft eccentric portion. Where ball or roller bearings are used it is desirable to prevent the hearing from running immersed in the liquid so that at least for such bearings the flow through the bearing should be restricted.

As already stated the inner rotor has a plurality of circumferentially-spaced apex portions engaging the peripheral wall of the housing cavity to form working chambers between said rotor and said cavity wall. axially and radially movable sealing strips are required along said apex portions particularly if the rotary mechanism is used as an internal combustion engine. In order to maintain the effectiveness of these seals it is desirable to extend the liquid cooling passages within the rotor close to said apex seals so as to provide effective cooling of these portions of the rotor. cooling passages to the zone of each of its apex portions may not always be possible or desirable. In such case it is a further feature of the invention to provide good heat transfer means between said rotor apex portions and radially inward portions of the rotor which are cooled by circulation of cooling liquid therethrough. For this purpose each apex portion of the rotor is provided with a chamber in which a good heat transfer medium such as sodium or copper is placed to transfer heat inwardly from the rotor apex portions to the cooling liquid circulating through the rotor.

The cooling liquid becomes heated in passing through the rotor and therefore said liquid must be cooled before being recirculated through the rotor. A special heat radiator structure would generally be required for this purpose. A further feature of the invention comprises an arrangement for passing said heated cooling liquid in heat exchange relation with in dependently cooled walls of the engine thereby eliminating a separate radiator structure. Such independently cooled walls couid, for example, be a water-cooled housing cover or an air-cooled structure such as a flywheel. A particularly effective procedure for recooling the heated cooling liquid is provided by an arrangement in which the heated cooling liquid is In general,

Extension of the rotor thrown, for example, by the liquid pressure or by centrifugal force, against such an independently cooled wall.

Other objects of the invention will become apparent upon reading the annexed detail description in connection with the drawing in which:

FIG. 1 is an axial sectional view of a rotary combustion engine embodying the invention, said view being taken along line 1-1 of FIG. 2;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is a transverse view of a modified rotor construction;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a view similar to FIG. 3 of another rotor construction;

FIGS. 6 and 7 are schematic axial sectional views illus trating further modifications of the invention;

FIG. 8 is a schematic axial sectional view illustrating an arrangement for recooling the heated cooling liquid;

FIG. 9 is a partial view illustrating a modification of FIG. 8.

FIG. 10 is a view of a still further arrangement in which the bearing between the inner rotor and the shaft eccentric portion consists of two axially-spaced parts.

Reference is first made to FIGS. 1 and 2 of the drawing which discloses a rotary internal combustion engine comprising a fixed outer member 10 forming a housing having flat end walls 12 and 14 and a shell 16 interconnecting the outer periphery of said end walls. Said end Walls and shell form an inwardly opening cavity 18 therebetween and the inner peripheral wall of said shell has a multi-lobed profile. As seen in FIG. 2, the cavity 18 has two lobes. A shaft 20 extends through the cavity 18, said shaft being supported by bearings 22 and 24 in the housing end walls 12 and 14, the axis of the shaft being co-axial with the housing cavity 18. The shaft 20 has an eccentric portion 26 on which an inner member 28 is rotatably supported, the bearing or bearing surfaces between the inner rotor 28 and eccentric portion 26 being indicated at 30. The rotor 28 extends radially into the housing cavity 18 and has flat end surfaces disposed adjacent to the cavity end walls 12 and 14. The rotor 28 also has a plurality of circumferentially-spaced apex portions 32 (three such apex portions being illustrated in FIG. 2) having sealing strips 34 which continuously engage the peripheral wall of the cavity 18 to form a plurality of working chambers 36 between said rotor and said peripheral wall. An external gear 38 is fixed to the end wall 14 and is co-axially disposed about the shaft 20, said gear having an axially extending portion 40 forming a bearing bushing for the shaft bearing surface 24. An internal gear 42 is co-axially secured to the inner rotor 28, said gear surrounding the gear 38 and meshing therewith. The engine also includes counterweights 44 secured to the shaft 20.

During engine operation the inner rotor 28 rotates about the axis of the shaft eccentric portion 26 and with said eccentric portion rotating about the axis of the shaft whereby the rotor has a rotary planetary motion within the cavity 18 of the outer member 10. The gears 38 and 42 enforce the relative motion of the inner and outer members 28 and 10 and between the inner member and the shaft 20. With the arrangement shown the diameter ratio of the gears 42 to 38 is 3:2 so that each revolution of the inner member or rotor 18 about the axis of shaft 20 is accompanied by three revolutions of said shaft.

The engine also includes an intake port 46 for a fuelair combustible mixture, an exhaust port 48 and a spark plug 50 for igniting the combustion mixture. During engine operation the working chambers 36 vary in volume to provide the usual strokes of a four-cycle combustion engine, namely the strokes of intake, compression expansion and exhaust as is more fully described in copending application Serial No. 774,517 filed November 4 17, 1958, now US. Patent 2,988,065 granted June 13, 1961.

The rotor 28 is cooled by circulating a cooling liquid therethrough. The cooling liquid is supplied through a passage 52 in the end wall 12 which terminates in an annulus 54 at the shaft bearing 22. From the annulus 54 the liquid is supplied by a passage 56 through the shaft 20 and its eccentric portion 26 to the bearing 30 between said eccentric portion and the rotor 28. The rotor 28 is provided with an internal cavity or passage arrangement 58. The internal cavity or passage 58 of the rotor has an inlet at an annulus 60 disposed at the bearing 30 and registering with the shaft passage 56 and has an outlet at a second annulus 62 also disposed at the hearing 30, this second annulus registering with a shaft outlet passage 64. From the shaft passage 64 the cooling liquid discharges into the housing chamber 66 for the counterweight 44 at the right end (as viewed in FIG. 1) of the engine and from this chamber through a passage 68 to a cooling radiator (not shown) from which the recooled liquid is returned to the engine through the supply passage 52. Liquid flowing along the bearing surface 24 also flows out through the chamber 66. Similarly liquid flowing along the bearing 22 from the annulus 54 can flow into the counterweight chamber 69 and then out through a passage 71.

This circulation of the cooling liquid is produced by a pump (not shown). If the outflow of the cooling liquid from the rotating parts is at a larger radius than the inflow of the cooling liquid then the centrifugal forces on the liquid help the liquid circulation or can be used to provide the pumping pressure.

As can be best seen in FIG. 2 the liquid cooling passage 58 within the rotor 28 extends to and along a region adjacent each rotor apex portion in order to effectively cool the region of each rotor adjacent to its apex seals 34.

Since the rotor 28 has a bore therethrough for the hearing 38 cooling liquid can escape therealong out the ends of the rotor 28 into annular chambers 70 and 72 at said ends. Annular seal means 74 and 76 are provided between the end walls 12 and *14 and the adjacent end faces of the rotor 28 to prevent leakage of the cooling liquid radially outwardly therebetween into the working chambers 36.

Each annular seal means 74 and 76 prefearbly comprises a thin walled flexible ring which has one edge secured to an end face of the rotor 28 and has its other edge urged into contact with the adjacent end wall 12 or '14 by the elastic stress in said ring and by the pressure of the liquid coolant. Each seal ring 74 and 76 is disposed radially outwardly of the bearing surfaces 30 and the inlet and outlet openings 68 and 62 for flow of cooling liquid into and out of the rotor 28. In addition the seal ring 76 (on the same side of the rotor member 28 as the gearing 38 and 42) is disposed radially outwardly of the teeth on the radially outer or internal gear 42.

The liquid used for cooling the rotor preferably also has lubricating properties whereby said liquid also serves to lubricate the bearing 30 and can be used to lubricate the shaft bearings 22 and 24.

In FIGS. 1 and 2 the cooling liquid flows directly through the rotor 28. In certain applications of the rotary mechanism such direct liquid flow is not needed particularly if the rotor apex portions 32 are not too far from the shaft eccentric 26. If this is the case then the rotor passage 58 can be eliminated and the rotor cooled by flow along the bearing 30 from the shaft passage 56 to the shaft passage 64. Also axial grooves 78 could be provided in the bearing 20 for supplying liquid'coolant directly from the annulus 54 to the annular chamber 70 from which it would flow through the bearing 38 to the annular chamber 72 and then by the passage 79 to the counterweight chamber 66. With this latter arrangement the shaft passages 56 and 64 could be eliminated. As already indicated the seal rings 74 and 76 serve to provent flow of liquid coolant radially outwardly from the chambers and 72.

FIGS. 3 and 4 disclose an arrangement for effective cooling of the apex portions 32 of the rotor 28 and the adjacent seal strips 34. Thus in FIGS. 3 and 4 the rotor 28 is provided with relatively large passages adjacent to its apex portions 32 and a pair of spaced passages 82 provide communication between each apex passage 80 and an annular groove 84 formed in the inner periphery of the rotor. A bushing 86 is secured to the inner periphery of the rotor, said bushing having openings 88 therethrou-gh communicating with the groove 84. The bushing 86 is fitted about the shaft eccentric 26 to provide the bearing 30 therebetween. if desired the bushing 86 could be secured to the eccentric 26 rather than to the rotor or said bushing may be a floating bushing. The eccentric 26 has supply and return passages 80 and 92 for the cooling liquid which end in recesses 94- and 86 respectively at the periphery of said eccentric. The openings 88 in the bushing communicate successively with the supply and return recesses 94 and 96 in the eccentric whereby liquid coolant circulates through the rotor annular groove 82. In addition because of the planetary motion of the rotor the liquid coolant is thrown into or out of the rotor apex passages 80 through the passages 82 depending on the direction of the acceleration of the particular apex passage 80 as a result of the planetary motion of the rotor.

In FIG. 5 the rotor 28 is illustrated as having a shape in which the rotor apex portions 32 are extremely remote from the periphery of the shaft eccentric portion 26 and the cross-section of the rotor apex portions is quite narrow. With a rotor of this shape it is difficult to provide cooling liquid passages of adequate size to the rotor apex portions. In lieu of cooling liquid passages at the rotor apex portions, in FIG. 5 each rotor apex portion is provided with a cavity 98 which is sealed instead of being connected to the annular groove 84 by the passages 82 as is FIGS. 34. Each of the sealed cavities 98 is at least partially filled with a good heat transfer material 99 as for example sodium or copper. With this arrangement of FIG. 5 the heat transfer material 99 transfers the heat inwardly where it is absorbed by the cooling liquid flowing through the groove 8 The structure of FIG. 5 is otherwise like that of FIGS. 3 and 4.

P16. 6 discloses an arrangement in which the delivery and supply of the cooling liquid to the inner rotor 28 is through the end walls of the housing directly to passages in the shaft eccentric portion 26 instead of through the main portion of the shaft. Thus in FIG. 6 a supply passage 100 extends through the end Wall 12 and terminates in an annular space 102 in a portion of the end wall facing the shaft eccentric 26. From said annular space 102 the cooling liquid flows through the passage 104 in the shaft eccentric 26 which in turn communicates with the inlet end of a passage arrangement 166 within the inner rotor 28. The outlet end of said rotor passage 106 com municates with a passage 108 within the shaft eccentric 26, said passage 108 in turn communicating with an outlet passage 110 in the end wall 14 or more particularly in the bushing 40 secured to said end wall. An annular space 112 is formed across the end of the shaft eccentric passage 108 facing the outlet passage 1 10. At the same time that the cooling liquid circulates through the rotor passage 106 from the supply passages 100 and 104 and discharges through the passages 108 and 110, a portion of said liquid will fiow through the shaft bearings 22 and 24 and eccentric bearing 30 to lubricate said bearings. As in FIG. 1, the seal rings 74 and 76 prevent flow of the cooling liquid radially outwardly into the working chambers of the rotary mechanism.

As illustrated the annular space 102 is formed in the end wall 12. However, the annular space 102, like the annular space .112 could be formed in the adjacent end surface of the shaft eccentric 26. Similarly, the annular space 112 could be formed in the adjacent surface of the end wall instead of in the surface of the shaft eccentric 26.

The annuli 10-2 and 112 could also be formed in the end faces of the inner rotor 28. This arrangement is itlustrated in FIG. 7. The cooling liquid circuit for the rotor 28 as shown in FIG. 7 is otherwise like that of FIG. 6.

It also may be desirable to provide an independent coolant circuit for the shaft 20 and its eccentric 26. This latter feature is also incorporated in FIG. 7. For this purpose a liquid coolant is supplied through a pipe 114 co-axially supported in a bore 116 in the shaft 20. From the pipe 114 the coolant enters a passage arrangement 118 in the shaft eccentric 26 and returns to the annular passage 120 in the shaft 20 between the pipe 114 and the bore 116.

Referring now to FIG. 8, the cooling liquid for the inner rotor 28 is supplied to an internal cavity or passage arrangement 122 within the rotor 28 through passages 12 1 and 126 in the shaft and shaft eccentric and is returned to the shaft eccentric by passage .128. From the passage 128 the heated liquid coolant flows through shaft passage 130 into a passage 132 in a shaft counterweight 44a. The heated liquid coolant is thrown out by centrifugal force through a nozzle 134 at the outer end of the passage 1'52, said liquid striking a surface 136 of a wall which has a passage 138 forming part. of another and independent cooling circuit. An outflow passage for the recooled cooling liquid is shown at 140.

Another arrangement for recooling the cooling liquid is shown in FlG. 9 in which the shaft return passage 130 for the cooling liquid communicates with a passage 142 in a shaft counterweight 44b. This counterweight has fan blades 144 which function as a pump to blow air between the blades to cool the counterweight thereby cooling the liquid flowing therethrough. The recooled liquid discharges through the shaft outlet passage 146.

For simplicity the gearing 38, 42 interconnecting the inner rotor with the outer member or housing is not shown in FIGS. 8 and 9.

It is apparent that with the arrangement of FIGS. 8 and 9 there is no need to provide a separate radiator to cool the heated cooling liquid before recirculating said liquid back through the inner rotor 28.

In FIG. 10 the cooling liquid is supplied through passages 174 and 176 in the shaft 20 and its eccentric 26. The passage 176 terminates at the periphery of the shaft eccentric 26 at the center of the bearing between the shaft eccentric and the inner rotor 28. This bearing is a roller hearing which consists of two sets of rollers 178 and 180, said two sets of rollers being held axially spaced apart by a cage 18 2. The cage 182 has a gap 184 in the middle which registers with the passage 176. The rotor 28 has an internal passage arrangement including a passage 185 communicating with the gap 184 and outlet passages 186 which communicate with the annular chamhers 70 and 72 at the rotor end faces. The cooling liquid flows out from the chambers through the passages indicated at 188 in the end walls 1 2 and 14 for return to the supply passage 176.

The cage 182 is such as to restrict flow of the liquid coolant between the bearing rollers 178 and so that only a small flow of said liquid is used to lubricate said bearing. Hence, the cage 182 prevents the rollers from running immersed in said liquid.

As in the other forms of invention the seal rings 74 and 76 prevent flow of the cooling liquid into the working chambers of the rotary mechanism from the annular chambers 70 and 72.

While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We

aim in the appended claims to cover all such modifications.

We claim as our invention:

1. A rotary mechanism comprising an outer member having axially-spaced end walls and a peripheral wall interconnecting said end Walls to provide a cavity between said Walls; a shaft coaxial with said cavity and having an eccentric portion; an inner member extending into said cavity with its end surfaces disposed adjacent to said end walls; bearing means supporting said inner member on said shaft eccentric portion so as to rotate about the axis of said shaft eccentric portion and so as to have a planetary motion relative to the outer member during operation of the mechanism, said inner member having circumferentially-spaced apex portions engaging said peripheral wall to form a plurality of working chambers therebetween and said inner member having internal passage means with inlet and outlet ports; passage means for supplying a cooling liquid having lubricating properties to said inlet port for flow of said cooling liquid through said internal passage means of the inner member and for supplying a portion of said liquid to said bearing means for lubrication thereof; gearing interconnecting said inner and outer members; and annular seal means carried by the inner member at an end surface thereof and having sealing engagement with the adjacent end wall of the outer member, said annular seal means being disposed radially outwardly of said inlet and outlet ports, radially outwardly of said gearing and radially outwardly of said bearing means.

2. A rotary mechanism as recited in claim 1 in which said gearing comprises an external gear fixed to said outer member co-axially with said shaft and an internal gear fixed to said inner member co-axially with said shaft eccentric portion and in which said annular seal means is disposed radially outwardly of the gear teeth of said internal gear.

3. A rotary mechanism as recited in claim 2 in which each said annular seal means comprises a ring which is elastically stressed so as to maintain sealing contact pressure.

4. A rotary mechanism as recited in claim 3 in which fluid pressure on the radially inner side of each seal ring is effective to increase the sealing contact pressure.

5. A rotary mechanism as recited in claim 1 in which said inner member and shaft eccentric portion both have end surfaces facing the inner surface of the adjacent end wall and at each end wall at least one of said surfaces has an annular chamber disposed radially inwardly of the adjacent annular seal means and in the flow path of said cooling liquid for the inner member.

6. A rotary mechanism as recited in claim 5 in which the supply and return of cooling liquid to and from said annular chambers is through the adjacent end Walls.

7."A rotary mechanism as recited in claim 5 in which at least a portion of said cooling liquid enters one end of the bearing between the inner member and shaft eccentric from one of said annular chambers and at least a portion of said liquid flows from the other end of said bearing into the other of said chambers.

8. A rotary mechanism as recited in claim 1 in Which passages are provided in said shaft and shaft eccentric portion, said passages terminating at the periphery of said eccentric portion for delivery and return of said cooling liquid to and from said inner member passage.

9. A rotary mechanism as recited in claim 1 in which the bearing between said inner member and shaft eccentric portion comprises two sets of bearing rollers axially spaced apart and in which the inner member passage communicates with the space between said two sets of rollers so that said space is in the flow path of the cooling liquid.

10. A rotary mechanism as recited in claim 1 and including means providing a cooling flow path through the shaft eccentric portion independent of the cooling flow path through the inner member.

11. A rotary mechanism as recited in claim 1 in which said mechanism has an element cooled independently of said inner member; and means for causing the cooling liquid, after passing through the inner member, to flow in heat exchange relation with said element.

12. A rotary mechanism as recited in claim 11 including means providing a rotating passage for the cooling liquid after its circulation through the inner member, said rotating passage having an opening directed towand said element such that the centrifugal force on said liquid acts to direct said liquid against said element.

13. A rotary mechanism as recited in claim 1 in which said inner member has a plurality of cavities containing a good heat transfer medium for transferring heat to the cooling liquid circulating through said inner member.

References (Iited in the file of this patent UNITED STATES PATENTS 1,228,806 Morris June 5, 1917 1,636,486 Planche July 19, 1927 2,871,831 Patin Feb. 3, 1959 FOREIGN PATENTS 103,413 Germany June 12, 1899 9,359 Great Britain 1915 583,035 Great Britain Dec. 5, 1946 

